At a “bra brunch” celebrating the latest Heidi Klum Intimates campaign in L.A. on Thursday, the fashion mogul told Yahoo that there’s never a good reason for women to wear anything but their best lingerie — even on nights when they’re 99 percent sure nobody will be laying eyes on their undergarments. “You never know!” Klum says with her typical flair. “You just never know when the clothes are coming off, so it’s always good to be prepared.”

The model, who has been in a relationship with art dealer Vito Schnabel since 2014, is so adamant about this that she’s made a point of clearing anything that is even remotely unflattering out of her own closet.

“I get rid of things that are not so nice anymore,” Klum, 44, tells us. “It’s the same with old sweatpants and things like that. Get one nice one rather than four pairs where the knees and booty are totally stretched out. Sometimes it’s better to not be tempted by the things that you have in your closet that are not so good.”

Another thing that baffles the designer about undergarments is the fact that women admit to going months without washing their bras.

“Ew!” Klum says with a laugh. “It’s so close to the armpit though! You sweat in your chest, especially in the summertime. [And] sweat runs down from your pits right into your bra,” she adds, clearly grossed out. For the record, “I wash mine after four times wear,” she says.

Project Runway‘s size-inclusive new look

While the no-wash concept is not something Klum can get behind, what she can endorse, however, is the recent groundbreaking decision by Project Runway to include all sizes, from 2 to 22, on the show — even if it hasn’t necessarily been popular with the entire industry. This kicked off on last night’s premiere of the Lifetime show.

“I love it!” Klum says. “Some of the designers didn’t really love it, but I don’t really care because we all have to go with the times. We should have done this way earlier already.”

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Heidi Klum and Tim Gunn along with models of all shapes and sizes on the Season 16 premiere of Project Runway on Aug. 17. (Photo: Barbara Nitke/Lifetime)

Klum says the change, which brings models with a range of body types into the fold for the first time, is really helping to “make the show more real” and cater to the average woman, instead of just showing the stick-thin models. And while Klum rose to fame in the modeling world, she’s quick to remind us that she was never the stick-thin type.

“Before, it was just about model sizes. [That’s] how we were used to seeing models on the runway. They were all a certain size — even a size that I wasn’t allowed to be part of, to be frank,” she says. “People are always like, ‘What are you talking about?’ but I never got to do a lot of runway because I was already too voluptuous. I had too much chest. I have child-birthing-friendly hips,” says the mom of four. “That’s what people would always tell me.”

The Project Runway judge went on to explain that because she didn’t have the “boy body that was in at the time” (see: Kate Moss), even she had a difficult time fitting into what designers considered “in” and booking runway shows. “I think now everything is becoming more real,” she says of the shift in fashion to be more size-inclusive.

It’s also Klum’s opinion that those who are not hopping on board with the trend will be left behind. “A lot of the designers are not even showing at Fashion Week anymore this year,” she says. “Everything is becoming more real. It’s becoming more user-friendly. We are thinking more about all women out there.”

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Heidi Klum, working the runway at the 2002 Victoria’s Secret Fashion Show, says she missed out on a lot of runway work because she was curvier than her peers. (Photo: Getty Images)

At least that is the mindset of Klum, who herself is working to design more all-inclusive clothing. “I’m going to be at New York Fashion Week with my own line and that is also real women. So it’s not just going to be thin models. … I’m going to have models of different sizes … because I’m selling in supermarkets and real women are going to the supermarket. And while they are buying their eggs and their milk, they see my clothes. I want real women to dress great for a good price.” (Klum’s apparel line is being sold at Lidl, a discount supermarket chain based in Germany that opens its first U.S. store in June.)

Klum said the Project Runway designers did a “great job” of embracing the new rules of Season 16 and notes that she was even able to squeeze her own plug in for the average woman. “We actually did one challenge for my line and it was a beautiful plus-size model that we had and she — maybe I can tease that — was a winning look,” she says. “It was beautiful and it will be reproduced and people can buy it, so that was very nice.”

A recap of Thursday’s premiere of Season 16 of Project Runway:

The exception to her “no bloomers” rule

The former Victoria’s Secret Angel, who recently launched the fall-winter 2017 collection of her Heidi Klum Intimates, wants every woman in America to feel confident enough to cloak herself in nice lingerie.

“There’s no reason not to,” she says. “Don’t let your body hang-ups stop you.” She adds that the key to undergarment confidence is to find something that makes you feel beautiful but comfortable. “If you aren’t into lacey thongs or bodysuits with cutouts, then try a nice cotton piece. There is something out there for everyone. But you don’t have to wear bloomers,” she says with a laugh.

For Klum, less is more. “I’m a G-string girl” she tells us, not surprising us in the least. However, sometimes she opts for more coverage to avoid a Marilyn Monroe moment.

“I don’t like to wear big bottoms, but sometimes if I have a really short flowy kind of minidress on and the wind would come up or if you go up the stairs and someone could look underneath, I would rather have a nice lace on my butt than nothing. Otherwise it’s just cheeks.”

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We don’t want to speculate, but Heidi Klum may have gone for fuller coverage for her appearance on Good Morning America on July 6. (Photo: Splash News)

She also reveals that her biggest secret to keeping gravity from taking its toll on “the girls” is to sleep in something that gives support.

“I love wearing lingerie in the bed,” she says. “If you have a comfortable one, I think that’s good for your boobs to keep them in shape longer. A lot of girls don’t do that though at night, but if you try it, it will help.”

Already working to defend her title of Halloween Queen

We still have some summer left to go, but the so-called Celebrity Queen of Halloween is already hard at work on her Oct. 31 ensemble. And she promises us that this one will put those of years past to shame.

“It’s going to be very scary this year,” she says, revealing that she plans to be a bit more theatrical than with previous costumes. (Last year, she toned it way down by going as herself — with some clones.) “I have to do some rehearsing for this. Normally it’s just preparing, but this time I have to rehearse!”

Getting outfitted with prosthetics may involve an agonizing amount of hours spent in the makeup chair (she starts prep in the summer), but the German-born stunner doesn’t plan on stopping the tradition any time soon. In fact, she’s committed to continuing to take it up a notch year after year.

“I always try to top myself,” she admits. “Also, because people expect it. They are always looking forward to what I’m doing.”

And as an entertainer, Klum sees it as her responsibility to make people loosen up, especially in the face of the dark political times that the country is in. “I just like to entertain people period,” she says. “I like making people laugh. I like to inspire people to also come up with great costumes.”

And while for years she’s held the title of Halloween’s best dressed, Klum openly welcomes any and all competition to fight for her throne. “I always say, ‘Top me. Top me!'” she says. “Come and do something crazy!'”